how to connect TCL Smart TV to a 5-channel SKG amplifier

Without model numbers we can't know exactly what connections you have.
TV may have optical digital audio out or headphone analog audio output.
If the SKG doesn't have optical audio input then use the headphone output.
Check the TV manual on how to configure the TV to use the digital audio output. Often needs to be turned on, the TV speakers turned off, and the audio output type changed.
 
Sorry but I can't find any details about either of those online.
Assuming the TV has optical audio output only you will need either an optical to analog converter which will have a left and right analog audio output or an optical to 5.1 analog converter which will have 6 analog audio outputs. Which one you get depends on whether the SKG has a 5.1 analog input or just a 2.0 analog input.